Hello, I am trying to introduce my new cat to my first cat. They are both new to my home but my first cat was very social and easy going. Lily, my first cat was able to find a place easily. She has come from the animal shelter and responded well to coming home. However my newest cat who was given for free by her previous owner, AlG, is unable to find a place here. I live in a large home but am unable to give her her own seperate room to be in. The only other available room, which I did try already, is too cold for her to stay in. I am too worried that the AlG will be too cold to stay there unsupervised until she feels comfortable to explore the whole house. I have tried to quarantine her to let her feel comfortable but had no luck due to the drastic temperatures in both rooms. I have brought her in but I am confined to only one large room where I have both Lilys and AlGs food/water, litter and scratching posts. So far she has been hiding in the dark behind the couch or under the chair in the basement which is the colder room. I am trying to find a better way to introduce AlG to the house as as well as to Lily.

Lily who is 2 is more social possibly from being at the shelter and meeting many people from time to time. I was told that AlG has been an indoor cat for 5-6 years and had a previous playmate named Miko (also a cat).

I am very worried that AlG(cat in hiding) will not be able to eat or eliminate due to lack of her old playmate and home. I think that she has become so stressed from the car ride and introduction into a new home that she will not come around to me. She even refuses to look at me or anyone else and prefers to look at the wall. Should I try to quarantine AlG or Lily. I am concerned for the safety and well being of both cats and want them to get along nicely. Also I would like Alg to eat something soon or drink something, I believe that Alg is a bit dehydrated. please help.

ps sorry or the long post.im sort of new at this whole thing if there is any more information to know just let me know
Thank You